This invention relates to pharmaceutical compositions for use in the treatment of lesions resulting from Herpes Simplex Virus (HSV) infections.
Herpes simplex is an enveloped, Class I Double Stranded DNA Virus. It infects vertebrates and it is thought that by the age 21, up to 80% of the population are infected with the so-called Type I virus or Herpes simplex labialis hereinafter referred to as HSVI. The vital infection begins when a virion comes into contact with a host cell and attaches to it. The vital DNA and proteins then cross the membrane into the cytoplasm of the cell ending up in the nucleus where the vital nucleic acid interacts with the host cell's nucleic acid synthesising machinery to direct its own replication and the synthesis of vital proteins. The multiple components of the herpes virions assemble in stages resulting in the production of a new round of virus particles and the death of the cell.
Primary HSVI infection occurs normally as a result of direct mouth to mouth or hand to mouth contact with a carrier. The primary infection is widespread (e.g. a rash inside the mouth) and often goes unnoticed. Following infection, the virus particles travel by axonal flow to nerve ganglia within the maxillary branch of the trigeminal nerve (which supplies the muscles around the mouth) where they remain dormant.
The dormant virus can undergo reactivation at any time resulting in localized lesions--the characteristic "cold-sore". Reactivation factors include any occurences causing immunosuppression such as infection, stress, pregnancy, drugs etc.
The second strain of HSV is HSV II--(Herpes simplex genitalis) which give rise to lesions in the genital regions. HSV II is sexually transmitted and although HSV types I and II were originally separate they have become interchangeable due to aberrant sexual practices.
Infants can become infected with HSV II as a result of passage through the birth canal of an infected mother. Following infection with HSV II the virus remains dormant in the sacral ganglia.
A current treatment for HSV infections is use of the drug Acyclovir which acts to prevent viral replication by blocking the action of the vital DNA polymerase. Though very effective, this drug is expensive, available only on prescription, and is generally recommended for use only under close medical supervision.